Ethylcyclohexane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005-09-16 - 2005-10-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Molecular formula
C8H16
Molecular weight
112.21*5
CAS number
1678-91-7
Purity
99.5% (GC)

Analytical monitoring:

yes

Details on sampling:

Test substance concentration was measured at the beginning of exposure, before and after water exchange, and at the end of exposure (two sets, at the time of preparation and after 24 hours as one set). At the time of preparation, separately collected test solutions were measured, and 24 hours after that, samples collected from the middle layer of one test vessel out of 4 test vessels for each test concentration were used. The test substance concentration was analyzed by gas chromatography (GC).

Vehicle:

no

Details on test solutions:

Preparation method of test solution
Purity correction was not made during preparation.
The test sample was added to an Erlenmeyer flask filled with test water to a concentration of about 50 μL/L using pushbutton micropipettes. After the addition, the mixture was sealed tightly so as not to generate a gas phase immediately, and stirred with a magnetic stirrer at room temperature for about 24 hours to prepare a saturated solution. Thereafter, it was allowed to stand at 20°C ± 1°C for about 1 hour, and the middle layer was collected and used as the test stock solution. A necessary amount of test stock solution and test water were mixed and stirred in a preparation container to prepare a test solution, which was then divided into each test container and immediately sealed using a watch glass.

Test organisms (species):

Daphnia magna

Details on test organisms:

Hatchling Daphnia magna produced from the adult subculturing at CERI Kurume, which is a descendant of Daphnia magna (Clone A) dispensed from Sheffield University in UK (Location: Sheffield S10 2UQ, United Kingdom), were used. Adults producing hatchings are those kept at the same water quality (dechlorinated tap water), water temperature (20 ± 1°C) and light/dark cycle (16 hours light/8 hours dark) as the test conditions (24 days old). A group (lots) with an adult survival rate of 100% was used. During subculturing, Chlorella vulgaris was fed at a rate of 0.1 to 0.2 mg C (organic carbon content) / day per daphnia once daily. The 48h EC50 of the acute immobilization test of potassium dichromate (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) which was carried out to confirm the reproducibility of the test system (carried out from August 8 to August 10, 2005) was 0.283 mg/L. This value was within the specified range of the background data at CERI Kurume (average ± 2 × standard deviation: 0.113 to 0.351 mg/L) [mean ± standard deviation was 0.232 ± 0.059 mg/L (n = 50)] .

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20.0°C to 20.1°C

pH:

7.9–8.0

Dissolved oxygen:

8.7–9.0 mg/L

Nominal and measured concentrations:

Measured:
0.21, 0.32, 0.485, 0.632, 0.975

Details on test conditions:

Apparatus and equipment
Apparatus
Test container: Tall-petri dish (inner diameter 8.0 cm, depth 5.0 cm)
Also, to prevent entry of dust and volatilization of the test solution, the petri dish was covered with a watch glass and sealed.
Test equipment
Constant temperature bath: Plastic water bath
Heating and cooling unit (HCA 250 type, Sato Craftworks Co., Ltd.)
Exposure conditions
Method
The test organisms were exposed to the test solution containing the test substance.
The test was carried out in a sealed semi-static type in which the total amount of test solution was exchanged 24 hours after the start of exposure.
Control group
Control group containing only test water not containing the test substance was provided.
Number of test organisms
20 animals / test concentration(5 animals × 4 test vessels)
Test solution volume
Approximately 1,000 mL/test concentration (about 250 mL × 4 test vessels)

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.667 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

0.975 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

0.485 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Validity criteria fulfilled:

yes

Conclusions:

In a 48-h acute toxicity study according to OECD Guideline 202, water fleas (Daphia magna) were exposed under semi-static conditions to analytically measured test concentrations of ethylcyclohexane.
The 48h-EC50 was 0.67 mg/l based on the geometric mean value of the measured concentrations (95% confidence interval between 0.485–0.975 mg/L).

Executive summary:

In a 48-h acute toxicity study according to OECD Guideline 202, water fleas (Daphia magna) were exposed under semi-static conditions to analytically measured test concentrations of ethylcyclohexane.

The 48h-EC50 was 0.67 mg/l based on the geometric mean value of the measured concentrations (95% confidence interval between 0.485–0.975 mg/L).

Description of key information

Daphnia magna:

In a 48-h acute toxicity study according to OECD Guideline 202, water fleas (Daphia magna) were exposed under semi-static conditions to analytically measured test concentrations of ethylcyclohexane.

The 48h-EC50 was 0.67 mg/l based on the geometric mean value of the measured concentrations (95% confidence interval between 0.485–0.975 mg/L).

Bay-shrimp:

The acute toxicity of ethylcyclohexane towards California bay shrimp was estimated in a static 96-hour test. The 96-hour LC50 was 3.1 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.67 mg/L